One‐Step Process for the Regiodivergent Double Hydrocyanation of 1,3‐Butadiene

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In industry, the two important nitrile starting materials, adiponitrile and 2‐methylglutaronitrile, are primarily manufactured through the well‐known DuPont process, which consists of a tandem sequence including first hydrocyanation, isomerization and second hydrocyanation. However, this mature process has the intrinsic defects of step efficiency and regioselectivity. Herein, we report a nickel‐catalyzed divergent, one‐step double hydrocyanation of 1,3‐butadiene to produce either adiponitrile or 2‐methylglutaronitrile in high regioselectivity. The key to this success lies in the highly tunable binding pockets of the bidentate phosphite ligands, which creates a geometrically defined coordination space around the nickel center. The first hydrocyanation that produces either the linear or branched alkenyl nitrile was identified as the selectivity‐determining step. Organometallic studies confirm the formation of well‐defined diphosphite nickel diene complexes in solution, and the role of ligands in dictating regioselectivity was further rationalized by DFT computations. This result provides the first example of a highly selective nickel‐catalyzed synthesis of adiponitrile and 2‐methylglutaronitrile from butadiene, and it also represents a high‐level of catalyst‐controlled regioselectivity via the fine‐tuning of ligand pocket geometry.